The invention relates to a device for producing solid aluminum chloride from gas containing gaseous aluminum chloride by means of a fluidized bed condenser connected up to an inlet pipe for the supply of a carrier gas and an outlet pipe for residual or waste gas, whereby between the inlet and outlet pipes there is a distributor plate with openings, at least one cooling facility, a feed or supply facility for the gas containing the gaseous aluminum chloride, and a facility for drawing off the solid aluminum chloride.
A process for producing solid aluminum chloride from gas containing gaseous aluminum chloride is known whereby the latter desublimates in a self regenerating fluidized bed of aluminum chloride particles. By desublimation is to be understood the direct transformation from the gaseous state to the solid state. The aluminum chloride rich gas also contains carbon dioxide, chloride, phosgene, carbon monoxide, solid and liquid oxy-chlorides and sodium chloride particles as well as solid aluminum oxide and solid carbon. The solid and liquid components are separated in a first stage at 200.degree.-600.degree. C. In a second stage at 150.degree.-250.degree. C. the aluminum chloride rich gas is passed into the fluidized bed. The bed itself is maintained at a temperature below the desublimation temperature, between 30.degree. and 100.degree. C., preferably between 50.degree. and 70.degree. C.
The above process refers to a device which is also known and which comprises a chamber surrounding the fluidized bed, an inlet for the carrier gas to suspend the solid aluminum particles, and a distributor plate to distribute the carrier gas, cooling devices, facilities to introduce the aluminum chloride rich gas and an outlet for removing the aluminum chloride particles from the fluidized bed. The said particles are between 40 and 420 .mu.m in size and the bulk density of the product is 1.2-1.7 g/cm.sup.3. The residual or waste gas from this device is at least partly recirculated and employed as carrier gas for fluidizing the bed.
In practice it has been found that the design of the component for distributing the carrier gas is of fundamental importance. A known form of this component is a tilted or inclined perforated surface which has holes in it to allow the carrier gas through.
This distributor has however been found very disadvantageous in practice. If the gas contains residual aluminum chloride and moisture, the holes in the surface soon become blocked. In the known device there is no facility which, during the recirculation process, precipitates out the fine aluminum chloride particles still present in the residual or waste gas. As part of this residual or waste gas should be used as carrier gas, the fine aluminum chloride particles or the rest of the aluminum chloride vapor dragged through by the carrier gas are lost during recirculation. This represents not only a loss of aluminum chloride but also a loss of condensation nuclei. In spite of this there is generally sufficient aluminum chloride in the residual or waste gas which in the course of time, in the conventional recirculation and re-use of the waste gas as carrier gas, leads to blockage of the holes in the distributor plate and, as this blockage occurs irregularly, results in regions in the unit where the bed is insufficiently fluidized. In addition, the pressure drop of the carrier gas is too small with this plate.
These disadvantages have a considerable effect on the economics of the device.
Furthermore, the known devices offer no possibility to introduce new condensation nuclei to the bed either at the start or during the condensation process.
A further disadvantage is that by having one single facility for removing the condensed aluminum chloride no selective removal according to particle size can be carried out.
It is therefore an object of the invention to develope a device of the above mentioned kind for the recovery of solid aluminum chloride from gas containing gaseous aluminum chloride but not having these disadvantages.